In the background art, a printing method using an elastic blanket is known well as a method for performing various kinds of printing on a curved surface of a to-be-printed body having curved surfaces, particularly a curved surface long in a longitudinal direction thereof. That is, a background-art blanket printing method performs printing as follows. Ink is applied onto an intaglio printing master plate made of steel and plastic. Excessive ink is removed from a protrusion portion by a spatulate scraper. The surface of a soft curved elastic blanket is pressed onto the printing master plate so that the ink left in a recess portion of a conductor of the printing master plate is transferred to the elastic blanket. This elastic blanket is brought into contact with the curved surface of the to-be-printed body.
In this case, however, the printing master plate is made of steel or plastic in the background art, and the excessive ink is scraped and removed from the protrusion portion after the ink is applied. Therefore, in order to surely retain the ink in the recess portion and transfer the ink to the elastic blanket satisfactorily, the depth of the recess portion has to be made large enough. This also results in deteriorating the printing accuracy.
When the printing master plate has a large difference in height between the protrusion portion and the recess portion, the surface of the elastic blanket is deformed so largely that printing cannot be performed accurately by the elastic blanket. In addition, particularly, in the case of an intaglio plate, the depth of the recess portion has to be made large enough to retain the volume of the ink surely. When the depth is large, the elastic blanket is also deformed largely. Further, due to the recess portion, the elastic blanket itself has to be soft enough to transfer the ink in the bottom portion of the recess portion to the elastic blanket, and to be adapted to the difference between the protrusion portion and the recess portion. Thus, the conditions become worse.
With respect to that point, when the printing master plate is a relief plate, it will go well if the ink is applied to its protrusion portion. Alternatively, the protrusion portion may be made of the ink itself. The difference in height between the protrusion portion and the recess portion can be reduced. As a result, a slightly hard blanket can be used as the elastic blanket itself. In addition, since the difference between the protrusion portion and the recess portion can be reduced, the deformation of the elastic blanket surface can be reduced, and the volume of the ink can be also adjusted finely. Thus, accurate printing can be performed. As for printing on a curved surface using a relief plate and an elastic blanket, various techniques have been developed, for example, as disclosed in JP-A-2-239972.